The present invention relates an arrangement, and a method, in a packet data communication system of connecting an end user local network and a packet data communication network. Particularly the invention relates to a network structure in a packet data communication system. The invention further relates to a packet data communication system including such arrangement(s) or a packet data communication system with a network structure for interconnecting local networks and a packet data communication network.
Cellular communication systems which, in addition to support communication of speech and a circuit switched data, also support communication of packet data are receiving more and more attention and several such systems are known. The GSM (Global System for Mobile Communication) system supports communication of packet data through the General Packet Radio Service (GPRS). Also the PDC-system (Personal Digital Communications) provides for packet data communication support through the PPDC (Packet PDC). Another such packet data communication service which is intended for the AMPS system is CDPD.
The GPRS of GSM uses a packet mode technique both for transfer of data and signalling and GPRS radio channels are defined which can be flexibly allocated. Time slots in a TDMA (Time Division Multiple Access) frame are shared by the users that are active and uplink and downlink are allocated separately. In GPRS as well as in other packet data communication supporting systems nodes are introduced for the management of packet data communication and in the present application such nodes are called packet data nodes. In GPRS the packet data node is called the serving GPRS support node (SGSN) which is at the same hierarchical level as an ordinary MSC (Mobile Switching Center) and it keeps track of the locations of individual mobile subscriber stations, performs security functions and access control. The SGSN is connected to the base station system (BSS) with frame relay. Another node is also provided in GPRS, the so called gateway GSN (GGSN) which provides for interworking with external packet switched networks and it is connected with SGSN via an IP-based GPRS backbone network.
For interconnecting a packet data communication network and for example a local area network of an end user expensive and complicated solutions are needed. Particularly specific routing equipment the only purpose of which is to connect an end user LAN with a packet data supporting network such as GPRS is needed. Such a router has to be supplied either by the end user himself or, as is mostly the case, by the GPRS operator. This is an expensive solution for the operator and furthermore it does not provide for any efficient scalability. According to the known solution a router is supplied for example by the operator and there has to be a link to the user from the GPRS system on which a tunnel protocol must run in order to enable the use of end user private IP addressing towards a mobile station. If Internet access is wanted, there has to be a link from GPRS to an Internet Service Provider and another router from Internet towards the end user communicating with a further router as referred to above providing a link to Internet from the end user. From SGSN and to GGSN, as defined above, there is a physical link via the GPRS backbone and a GTP (GPRS tunnelling protocol e.g. described in GSM 09.60 Vers. 5.0.0, Draft TS 100, 960 Vers. 5.0.0 (1998-01) by ETSI (European Telecommunications Standard Institute)) link is used from SGSN to GGSN. The solution is centralised and it requires extra tunnelling to the LAN of the end users, thus a tunnel runs from a GGSN to a tunnel device, the tunnel end point of which has to be reachable through use of public IP addressing or by use of GPRS operator supplied addressing. This is a requirement since otherwise the tunnel end point can not be reached from the GGSN. If routing is provided through Internet, encryption requirements may be imposed. The tunnel ends with a tunnel end point device which may be end user supplied or operator supplied and it runs an unspecified tunnel protocol which may include encryption. This is managed by the end user in turn communicating with the end user equipment which in turn communicates with the mobile station.
The known centralised solution is even more disadvantageous if the end users use private IP addressing schemes. In addition to the high costs of equipment for the operator, a lot of physical space is needed which in turn also is expensive and unpractical for the operator. Still further, since the equipment is centralised, the impact will be very large in case of functional disturbances. It is also a drawback that the operator is dependent on routing equipment which involves high costs.
What is needed is therefore an arrangement for interconnecting an end user local network and a packet data communication network which facilitates the provision of interconnection for the operator and through which a simple and cheap solution can be provided for the operator. Still further an arrangement is needed which enables a high degree of scalability of the system. Still further an arrangement is needed which does not require the operator to buy and pay for expensive and space demanding equipment which often only can be used for the particular dedicated purposes. Still further an arrangement is needed which removes the drawbacks of the hitherto known solutions which are centralised leading to severe impacts in the case of functional disturbances etc. Particularly an arrangement is needed through which the buying of dedicated equipment can be avoided to a high degree for the operator. An arrangement is also needed through which the structure is simplified also when end users use private IP addressing schemes.
Particularly an arrangement is needed through which the costs for the total system can be reduced and which enables a simple solution solving end user IP address overlapping in case IP addressing schemes are used. Particularly an arrangement is needed through which the costs can be reduced for the operator and in practice also for the customers since they will pay for what they actually use.
A cellular communication system supporting packet data communication having a network structure allowing an interconnection of the packet data network and end user networks fulfilling the aims as discussed above is also needed.
Still further a method of interconnecting a packet data communication network and an end user local network fulfilling the above discussed objects is also needed.
Therefore an arrangement for interconnecting an end user local network and a packet data communication network comprising a packet data network backbone, is provided, at least comprising one packet data node with a serving functionality for handling packet data communication, the arrangement further including a gateway functionality for providing communication with external networks. It comprises at least one virtual distributed node which provides the gateway functionality. The virtual distributed node comprises an interworking node device including converting means for converting between a communication protocol for local network end user communication which uses a user level data packet format and an internal packet data protocol using an internal packet data format. The virtual distributed node includes a management functionality for managing the interworking node device. This management functionality is executed in, or localized to, a packet data node with a serving functionality and the packet data network is used for communication. Thus the gateway functionality is moved to the interworking node device which generally is provided by the user and the management thereof is provided through the serving packet data node. The management functionality particularly comprises a management system which executes in a serving packet data node. The management functionality can be provided and executed in a number of serving packet data nodes and a plurality of serving packet data nodes may also be able to manage a plurality of interworking node devices for reasons of redundancy. In a most advantageous embodiment the virtual distributed node/nodes is/are managed by the operator of the packet data communication system. The management can of course also be handled in other manners, but operator management provides for a particularly advantageous implementation.
A public or third party data communication network such as for example Internet may also be integrated with the packet data communication system backbone network as an interconnect or as an interconnecting data network.
According to different embodiments the internal packet data frames may be, or require being, encrypted. In that case the interworking node device has to convert the internal packet data frames to/from user level packet data frames, thus also handling the encryption. Encryption is particularly needed if a part of the network is a public or third party data communication network such as Internet. The encrypted frames may be so called IP-sec-frames. This is particularly the case when an end user uses a private IP addressing scheme, the external network being Internet. The same is of course applicable in case the public or third party data communication network is some other network than Internet or an intranet.
The inventive concept can be implemented for different cellular communication systems including a packet data communication supporting functionality such as for example GPRS. In that case the packet data node with a serving functionality is the so called serving GPRS support node SGSN. This node is connected to a base station subsystem BSS and the internal packet data communication protocol that is used is the GTP protocol. The virtual distributed node providing the gateway functionality can thus be said to replace the network gateway node GSN, also called GGSN. According to the present invention the virtual distributed node including the interworking node device, which is managed from a SGSN, thus replaces the conventional GGSN, the management of the entire system still, in an advantageous implementation, being handled by the operator, the interworking node device, however, physically and financially being taken over by the end user.
In an alternative embodiment the packet data communication system is packet PDC, PPDC, in which case the serving packet data node is a packet-mobile switching center, P-MSC. In still another implementation the concerned system is the CDPD as discussed above. Of course the invention is also applicable to any other packet data system using a network structure which is similar to what has been described above, including serving and gateway node types, such as for example the GPRS structure.
The inventive concept can e.g. also be implemented in UMTS (Universal Mobile Telephone System). In an alternative implementation the virtual distributed node or nodes is/are managed by the end user.
Therefore also a cellular communication system supporting packet data communication which comprises a number of packet data nodes with a serving functionality for handling packet data communication, communicating with the base station subsystem, and including a gateway functionality for providing communication with external data networks is provided. The system also provides for communication with end user local networks. The communication system comprises a number of virtual distributed nodes providing a gateway functionality and comprising an interworking node device which includes converting means for converting between a communication protocol for local network end user traffic, which protocol uses a user level data packet format, and an internal packet data protocol using an internal packet format. Each virtual distributed node is also provided with a management functionality for managing the interworking node device. Said management functionality for a number of interworking node devices, i.e. one or more, is executed in a number of packet data nodes comprising a serving functionality. The packet data network backbone is used for communication. According to different embodiments the management functionality is provided in a plurality of serving packet data nodes for managing at least one interworking node device, i.e. a plurality of serving packet data nodes may all be able to manage one interworking node device for redundancy reasons or one serving packet data node may be able to manage one or more interworking node devices or a plurality of interworking node devices as well as one interworking node device either may be manageable from one packet data node with a serving functionality or by a plurality of packet data nodes with a serving functionality. The solution may be the same throughout the system or different solutions may be implemented over the system, for example taking into consideration the redundancy needed at the actual location.
Advantageously the virtual distributed nodes are managed by the operator of the cellular communication system supporting packet data communication. In a particular implementation a public or third party data communication network is integrated with the cellular communication system supporting packet data communication the backbone network acting as an interconnecting data network. The public or third party data communication network may for example be Internet. Intranets may also be integrated in a similar manner.
In a particular implementation a number of internal packet data frames provided to a number of interworking node devices for conversion are encrypted, e.g. because of an external data communication network being connected. The interworking node device does then convert said internal packet data frames to (and from) user level packet data frames for end user communication. Systems implementing the inventive concept may for example be GPRS, PPDC, CDPD, UMTS etc., the main thing being that the structure is such that it needs nodes with a serving functionality and a gateway functionality.
A method of interconnecting an end user local network and a packet data communication network comprising a packet data network backbone is therefore also provided. The packet data communication network comprises a number of packet data nodes including a serving functionality and it also includes a gateway functionality for external communication. The method includes the steps of; introducing an interworking node device to provide a gateway functionality; executing the management of said interworking node device in a number of packet data nodes having a serving functionality; using an internal data communication protocol for communication between a packet data node with a serving functionality and an interworking node device; using a communication protocol for communication between the interworking node device and the end user of a local network, e.g. a Local Area Network (LAN), in said interworking node device converting between the end user communication protocol and the internal data communication protocol so that communication between a packet data node with a serving functionality and an end user local network can take place without the use of specific tunnelling protocols and intermediate, centralised, routing means.
Particularly the method includes the step of managing an interworking node device from a plurality of packet data nodes for reasons of redundancy. Even more particularly the method includes the step of managing a plurality of interworking node devices from one and the same packet data node with a serving functionality. Most particularly the method includes the step of providing for managing of the interworking node devices, or the virtual gateway nodes, by the operator of the packet data communication system. In an advantageous implementation the method includes the steps of integrating a public or third party data communication network, such as for example Internet, or intranets, as interconnecting external networks. The method can be implemented in different packet data communication systems such as GPRS, PPDC or CDPD etc. as referred to above.
It is an advantage of the invention that a decentralised solution is used, thus reducing the consequences of malfunctions etc. It is also an advantage of the invention that the equipment can be customized and provided by the customer, on the customer premises and also physically located at the end user""s desired location and still it particularly may be handled or managed by the operator of the packet data system. Also a number of other advantages are provided for of which a number already have been described earlier in the application.